This apparatus relates to a machine such as a computer numerically controlled (CNC) machine. More specifically, the invention relates to a machine for machining small glass parts such as a side view mirror.
Machine tools such as an edge grinding apparatus typically include a grinding wheel, a holder for a blank, and a CNC device for controlling the grinding of the blank according to selected specification. The CNC machine tool may include a multi-axis, linear (X, Y axis) holder or a rotatable holder and a vertical (axis Z). The machine does not have to be limited to a CNC controlled machine, but could also be a cam design for use with simpler controls. The cutting tool is not restricted to standard turning or milling cutters, but also includes all mechanical, electronic and/or electromechanical devices used to modify the shape and/or properties of the workpiece. Examples of cutting tools include: end-mills, turning tools, grinding wheels, laser cutting beams, plasma beams and punch tools.
In a standard CNC glass grinding machine, the next raw part is held by a shuttle or operator, waiting for the machine to finish the current part. When the current part is complete, a clamp and/or vacuum must release and a shuttle or operator must unload the finished piece before loading the next raw part. After the next raw part is loaded and located, the vacuum and/or clamp must grab the part before the cycle can start.
The transferring, locating, relocating and aligning of parts requires time (loading time). For small parts, this loading time may even exceed the processing time. Current solutions use fine adjustment cylinders sensors, fine adjustment vacuum sensors and high speed shuttles to minimize the load time. Even with the best adjustment, most current systems require 6 or more seconds to load the parts. Some mirror parts can be processed in 3 to 5 seconds.
For small parts, grind time can exceed by a considerable amount the load/unload time. This greatly reduces the output of the system. This invention minimizes the waiting time by providing an auxiliary station for simultaneous unloading/loading while grinding. The apparatus comprises a means to locate the part away from the grinding head and accurately hold and index the part to the grind point. The apparatus also includes the integration of two stations into one by the use of multiple axis"". The CNC grinder head with high speed spindle for small internal radii is mounted to a linear horizontal axis X and linear vertical axis Z. Controls integrate the correct second axis Y, which is part of the holding mechanism, with the horizontal and vertical linear axis of the grind head, to grind the part.
A rotating table is used to rotate the two part holding mechanisms.
The table rotates +/xe2x88x92180xc2x0. Attached to the table are two glass locating/holding systems which also incorporate the second axis of the CNC system. Each position consists of a rotary servo axis, a lower vacuum pad, an upper vacuum clamp pad with ram and pneumatic cylinder. A locating means is also provided at the lower side of the vacuum pad or prior to the loading shuttle.
The part is loaded and located onto the outer positioned station, and the system is signaled that the part is ready. Vacuum switches on and the table will rotate, presenting the outer station to the grind head, at the same time presenting the previously finished part to the outside. During rotation, the outer station will clamp and the inner station will release. The grinding head will commence grinding of the new part. At the same time, the part is raised with vacuum, on the clamp. The operator (or automatic load system), loads a new part onto the vacuum pad, and then takes the finished part from the raised clamp. The system is signaled that the fresh part is ready when the other station is done grinding, the rotation occurs again.